Apparatus and method for determining public long code mask in a mobile communications system

ABSTRACT

An apparatus and method of assigning a public long code mask (PLCM) to a mobile terminal in a mobile communications network is provided. The invention comprises assigning a first PLCM type, when the PLCM for the mobile terminal is based on an international mobile station identification number that is based on a mobile identification number (MIN) associated with the mobile terminal and assigning a second PLCM type, when the PLCM for the mobile terminal is provided by a service provider.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. § 119(a), this application claims the benefit ofearlier filing date and right of priority to Korean Patent ApplicationNo. 2003-0034236 filed on May 29, 2003 and 2003-0055136 filed on Aug. 8,2003, the contents of which are hereby incorporated by reference hereinin their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus and method for generatinga public long code mask (PLCM) in a mobile communications system.

2. Discussion of the Related Art

Generally, in the cdma2000 communication system, a long code in forwardchannel is used in ciphering the forward channel and determining thelocation of a power control bit. Moreover, the long code in a reversechannel is used as an element for identifying each terminal. It alsoplays a role in reducing interference between subscriber terminals.

A long code is typically constructed with 42 bits. FIG. 1 is a blockdiagram of a general process of generating a long code and transmittinga signal. The long code, as shown in FIG. 1, is generated according to a42-bit long code mask. The generated long code undergoes modulo-2 innerproduct by a transmission signal. The long code mask is separatelygenerated per each channel.

The PLCM format used in the traffic channel is shown in FIG. 2 and FIG.3. FIG. 2 is a diagram of a PLCM format for a reverse fundamentalchannel of which radio configuration (RC) is 1 or 2 and a reversesupplemental code channel.

FIG. 3 is a diagram representing a PLCM format for a reverse fundamentalchannel, a reverse supplemental channel, a reverse dedicated controlchannel; a forward fundamental channel, a forward supplemental codechannel, a forward supplemental channel, a forward dedicated controlchannel, or a forward packet data channel.

Referring to FIG. 2 and FIG. 3, the PLCM format Includes PLCM_(—)37(M36˜M0) constructed with least significant 37 bits of the PLCM. ThePLCM_(—)37 can be divided into first least significant bits (M36˜M32)and second least significant bits (M31˜M0).

A base station can inform a terminal of how to generate the second leastsignificant bits M31˜M0 via an extended channel assignment message(ECAM). That is, if a PLCM type PLCM_TYPE in the ECAM is ‘0000’, themobile station sets the first least significant bits M36˜M32 as ‘11000’and generates the second least significant bits PLCM_(—)32 by performingthe following permutation of electronic serial number (ESN).

If ESN={E31, E30, E29, . . . , E2, E1, E0}, the second least significantbits PLCM_(—)32 are {E0, E31, E22, E13, E4, E26, E17, E8, E30, E21, E12,E3, E25, E16, E7, E29, E20, E11, E2, E24, E15, E6, E28, E19, E10, E1,E23, E14, E5, E27, E18, E9}.

If the PLCM_TYPE is ‘0001’, the first least significant bits M36˜M32 isset to ‘11011’ and the second least significant bits PLCM_(—)32 is setto PLCM_(—)32r which is a 32-bit value received through the extendedchannel assignment message (ECAM). The ESN is the only identifierallocated to a terminal in the cdma2000 system and is used for callprocessing.

The structure of an ESN is shown in FIG. 4. The ESN is constructed with32 bits. A manufacturer's code (MFC) is allocated to the mostsignificant 8 bits and a serial number (SN) of the terminal,manufactured by a corresponding manufacturer, is allocated to the leastsignificant 24 bits. A manufacturer's code is allocated to eachmanufacturer and is generically set up. If the number of terminals ofthe corresponding manufacturer exceeds the allocated SNs, a new MFC isallocated.

Meanwhile, it is expected that the 32-bits ESN will be exhausted as aresult of product overflow. Hence, a new identifier for identifying aterminal is provided to replace the ESN. The new identifier is a mobileequipment identifier (MEID).

FIG. 5 is a diagram of a structure of a MEID. A MEID is constructed with56 bits. A manufacturer's code (MFC) is allocated to most significant 32bits and a serial number (SN) of a terminal manufactured by thecorresponding manufacturer is allocated to least significant 24 bits.

In a related art method, a process for permutating the 32-bit ESN over a42-bit PLCM is used. When using a 56-bit MEID, it is impossible toinsert the MEID in the PLCM because the MEID is longer than the PLCM.

As such, when the MEID is used as the identifier for identifying aterminal instead of the ESN, the new method of generating a PLCM isneeded.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the invention, a method ofdetermining a public long code mask (PLCM) in a mobile terminalcomprises assigning a first PLCM type, when the PLCM for the mobileterminal is based on an international mobile station identification(IMSI) that is based on a mobile identification number (MIN) associatedwith the mobile terminal; and assigning a second PLCM type, when thePLCM for the mobile terminal is based on the IMSI that is based on avalue provided by a service provider.

According to one aspect of the present invention, the first PLCM type ispreferably not used when the mobile terminal is not in a home country.Alternatively, the second PLCM type is preferably not used when themobile terminal is not in a home network.

According to another aspect of the present invention, the PLCM comprisesa first portion and a second portion, wherein the second portion isdetermined from at least a part of the IMSI. Preferably, the secondportion of the PLCM comprises 34 bits. When the first PLCM type is beingused, the second portion of PLCM is determined from at least a part ofthe MIN when the first PLCM type is being used.

According to another embodiment of the present invention, a method ofdetermining a public long code mask (PLCM) in a mobile terminalcomprises assigning a first PLCM type, when the PLCM for the mobileterminal is based on a mobile equipment identifier (MEID) associatedwith the mobile terminal; assigning a second PLCM type, when the PLCMfor the mobile terminal is specified by a base station; assigning athird PLCM type, when the PLCM for the mobile terminal is based on aninternational mobile station identification (IMSI) that is based on amobile identification number (MIN) associated with the mobile terminal;and assigning a fourth PLCM type, when the PLCM for the mobile terminalis based on the IMSI that is based on a value provided by a serviceprovider.

According to one aspect of the present invention, the PLCM for themobile terminal comprises a first portion and a second portion.Preferably, the first portion comprises most significant bits and thesecond portion comprises least significant bits of the PLCM.

When the first PLCM type (e.g., PLCM type is equal to ‘0000’) isdesignated or assigned, then the PLCM value is calculated by applying ahashing algorithm to the MEID. The first PLCM type may be assigned whenthe mobile terminal is roaming. When the first PLCM type is assigned,the second portion of the PLCM comprises a hashed value of the MEID.

When the second PLCM type (e.g., PLCM type is equal to ‘0001’) isdesignated or assigned, then the PLCM value is provided to the mobileterminal by the base station. When the second PLCM type is assigned, thesecond portion comprises a value provided by the base station.Preferably, the first portion of the PLCM comprises ‘101’ and the secondportion comprises 39 bits.

When the third PLCM type (e.g., PLCM type is equal to ‘0010’) isdesignated or assigned, then the PLCM value is derived or based on theMIN in its least significant portion. Preferably, the third PLCM type isnot used when the mobile terminal is not in a home country. Also, whenthe third PLCM type is assigned, the second portion comprises a valuebased on a MIN associated with the mobile terminal. The second portioncomprise at least part of least significant digits of the MIN. Moreparticularly, the second portion may comprise least 10 significantdigits of the MIN or alternatively a 34 bit value. The first portion ofthe PLCM may comprise ‘11000001’ or alternatively, ‘11000XX1’, wherein Xis one of zero and 1.

According to one aspect of the present invention, the second portioncomprises least significant digits of the MIN in the second portion'sleast significant positions and comprises padding bits in the secondportion's most significant positions, when length of the MIN is smallerthan length of the second portion.

When the fourth PLCM type (e.g., PLCM type is equal to ‘0011’) isdesignated or assigned the PLCM is provided to the mobile terminal bythe service provider. In other words, the second portion of the PLCM isnot based on the MIN of the mobile terminal. Preferably, the fourth PLCMtype is not used when the mobile terminal is not in a home network.

According to one aspect of the present invention, when the fourth PLCMtype is assigned, the second portion comprises a 34-bit value and thefirst portion comprises ‘11000000’, or alternatively, ‘11000XX0’,wherein X is one of zero and 1.

According to another aspect of the present invention includes at leastone of the first, second, third, and fourth assigned PLCM types in afirst field of a data structure communicated to at least one of themobile terminal and the base station. Moreover, the invention alsoincludes a second field in a data structure communicated to at least oneof the mobile terminal and the base station, wherein a value associatedwith the second field indicates whether a first field is included in thedata structure, wherein the first field includes one of the first,second, third, and fourth assigned PLCM types.

According to another embodiment of the present invention, a method ofdetermining a public long code mask (PLCM) in a mobile terminalcomprises receiving from a base station a PLCM type indicator thatindicates a type of PLCM to be used in the mobile terminal; anddetermining at least part of the PLCM based on an international mobilestation identification (IMSI) when the PLCM type indicator is equal to apredetermined value. Preferably, the at least part of the PLCM based onthe IMSI comprises 34 bits. The IMSI is associated with a mobileidentification number of the mobile terminal, when the PLCM typeindicator is associated with a first value (e.g., ‘0010’), and the IMSIis associated with a value provided by the service provider through abase station, when the PLCM type indicator is associated with a secondvalue (e.g., ‘0011’).

According to another embodiment of the present invention, a mobileterminal for using a public long code mask (PLCM) comprises means forassigning a first PLCM type, when the PLCM for the mobile terminal isbased on a mobile equipment identifier (MEID) associated with the mobileterminal; means for assigning a second PLCM type, when the PLCM for themobile terminal is specified by a base station; means for assigning athird PLCM type, when the PLCM for the mobile terminal is based on aninternational mobile station identification (IMSI) that is based on amobile identification number (MIN) associated with the mobile terminal;and means for assigning a fourth PLCM type, when the PLCM for the mobileterminal is based on the IMSI that is based on a value provided by aservice provider.

According to yet another embodiment of the present invention, a mobileterminal comprises means for receiving from a base station a PLCM typeindicator that indicates a type of PLCM to be used in the mobileterminal; and means for determining at least part of the PLCM based onan international mobile station identification (IMSI) when the PLCM typeindicator is equal to a predetermined value. Preferably, the at leastpart of the PLCM based on the IMSI comprises 34 bits. The IMSI isassociated with a mobile identification number of the mobile terminal,when the PLCM type indicator is associated with a first value, and theIMSI is associated with a value provided by the base station, when thePLCM type indicator is associated with a second value.

These and other embodiments of the present invention will also becomereadily apparent to those skilled in the art from the following detaileddescription of the embodiments having reference to the attached figures,the invention not being limited to any particular embodiments disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is a block diagram of a method of generating a long code.

FIG. 2 is a diagram of a PLCM format for a reverse fundamental channeland a reverse supplemental code channel wherein radio configuration (RC)is 1 or 2.

FIG. 3 is a diagram of a PLCM format for a reverse fundamental channel,a reverse supplemental channel, a reverse dedicated control channel, aforward fundamental channel, a forward supplemental code channel, aforward supplemental channel, a forward dedicated control channel, or aforward packet data channel.

FIG. 4 is a diagram of a structure of an ESN.

FIG. 5 is a diagram of a structure of a MEID.

FIG. 6 is a diagram of a structure of an IMSI.

FIG. 7 is a diagram of a structure of 34-bit IMSI_S, in accordance withone embodiment of the invention.

FIG. 8 is an exemplary structure of a PLCM, according to a preferredembodiment of the present invention.

FIG. 9 is an exemplary structure of a PLCM, according to one embodimentof the present invention.

FIG. 10 is an exemplary structure of a PLCM according to anotherembodiment of the present invention.

FIG. 11 is an exemplary structure of a PLCM according to anotherembodiment of the present invention.

FIG. 12 is a flowchart for determining a PLCM, in accordance with oneembodiment.

FIG. 13 is a diagram illustrating a mapping of a least significant bitsof IMSI to the least significant 40 bits of a PLCM, according to oneembodiment of the invention.

FIG. 14 is a diagram illustrating a mapping of a decimal number to abinary value, in accordance with one embodiment.

Features, elements, and aspects of the invention that are referenced bythe same numerals in different figures represent the same, equivalent,or similar features, elements, or aspects in accordance with one or moreembodiments of the system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

To aid describing the present invention, certain exemplary parameternames, values, lengths and other attributes are being used to describethe channels, messages and fix or variable identifiers communicatedbetween mobile and base stations. It should be noted that such parameternames are for illustration purposes only, and that other names may beused to describe the same or similar function.

The present invention generates a PLCM using international mobilestation identity (IMSI) number uniquely allocated to each terminal toglobally identify a terminal. IMSI is provided in ITU-T E.212 asrecommendations related to numbering. ITU-T E.212 was established toallocate a generic number to each globally used terminal and to avoidseparate numbering rules in the respective countries by giving a uniformrule to the number.

FIG. 6 illustrates a structure of IMSI, In which IMSI preferablycomprises up to 15 digits or numerical characters. The most significant3 digits are allocated to a code for identifying a corresponding countryas a mobile country code (MCC). The remaining digits are the NationalMobile Subscriber Identity (NMSI). The NMSI comprises a mobile networkcode (MNC) and a mobile station identification number (MSIN). The MNCidentifies a network servicing a terminal. For example, the network maybe identified by a service provider providing communications service tothe mobile terminal. One provider may have several MNCs. A MSIN (mobilestation identifier number) is used for identifying a user terminal ineach network.

According to the preferred embodiment, IMSI_M is an IMSI that containsmobile identifier number (MIN) in the NMSI. The MIN is 34 bit numberthat is a digital representation of the 10-digit number assigned to amobile terminal and it may be associated with the mobile telephonenumber. IMSI_T is an IMSI that is not associated with the MIN. TheIMSI_T may be provided by the service provider. During operation of themobile terminal, on operational IMSI value (IMSI_O) is used which iseither the IMSI_M or the IMSI_T depending on the base stationcapabilities.

FIG. 7 illustrates IMSI_S digits according to a preferred embodiment ofthe present invention. An IMSI_S is preferably a 10-digit (34 bit)number derived from the IMSI, preferably from the IMSI_O. In thepreferred embodiment, if the IMSI is equal to or greater than 10 digits,least significant 10 digits of the IMSI become the IMSI_S. If the IMSIis smaller than 10 digits, ‘0’ is inserted in the front portion to meetthe 10 digits.

The 10-digit IMSI_S comprises IMSI_S1 (preferably 7 digits) and IMSI_S2(preferably 3 digits). The IMSI_S derived from the IMSI_O is preferablydesignated as IMSI_O_S, which is shown in FIGS. 8 and 9.

The following embodiments according to the present invention generatinga unique PLCM in a mobile terminal by using the above-described IMSI_S.Therefore, each of the terminals in the same mobile network is able tohave a unique PLCM.

In order to generate the PLCM, the ESN or MEID of the mobile terminalmay be used. Alternatively, a temporary IMSI can be used. Depending onthe base station requirements and limitations, the following PLCM types(PLCM_TYPE) can be defined. For purposes of describing the presentinvention, the PLCM_TYPE is the PLCM type indicator. The base stationsets the PLCM_TYPE to the corresponding type.

According to the preferred embodiment, the PLCM_TYPE is defined as‘0010’, for example, which is used in extracting operational IMSI(IMSI_O) from IMSI_M based on a MIN (mobile identification number). Inanother embodiment, the PLCM_TYPE is defined as ‘0011’, for example,which is used in extracting operational IMSI (IMSI_O) from true IMSI(IMSI_T). For example, the PLCM_TYPE of ‘0010’ is not used when themobile terminal is not in its home country. In other words, when the MCCof the mobile terminal is different from the MCC of the base station.Similarly, the PLCM_TYPE of ‘0011’ is not used when the mobile terminalis not in its home network. In other words, when either the MCC or MNCof the mobile terminal is different.

Referring to FIGS. 8 and 9, a method of generating a PLCM in accordancewith a preferred embodiment of the invention is provided. In case thatIMSI_O (operational IMSI) is extracted from IMSI_M, (e.g., in case thatPLCM_TYPE is ‘0010’), most significant 5 bits M41˜M37, for example, areset to ‘11000’. Two bits M36 and M35 following the most significant 5bits M41˜M37 are set to ‘00’, for example, to avoid collision with apreviously existing long code mask.

The two bits M36 and M35 can be set to ‘10’or ‘01’, for example, toavoid currently existing long code masks on all physical channels. Asubsequent bit M34 may be then set to ‘1’, for example, to bedistinguished from the case that IMSI_O is extracted from IMSI_T. Lower34 bits M33˜M0, for example, are set to the previously defined IMSI_S.

Referring to FIG. 9, a method of generating a PLCM in case that IMSI_O(operational IMSI) is extracted from IMSI_T, (e.g., PLCM_TYPE ‘0011’) isprovided. Most significant 5 bits M41˜M37, for example, are set to‘11000’. Two bits M36 and M35, for example, following the mostsignificant 5 bits M41˜M37, for example, are set to ‘00’ to avoidcollision with a previously existing long code mask.

The two bits M36 and M35 can be set to ‘10’ or ‘01’, for examples toavoid currently existing long code masks of physical channels. Asubsequent bit M34, for example, may be then set to ‘0’ to bedistinguished from the case that IMSI_O is extracted from IMSI_M. Thelower 34 bits M33˜M0, for example, are set to previously defined IMSI_S.

Referring to FIGS. 10 and 11, in another embodiment, 1^(st) and 2^(nd)bits of a PLCM are set to ‘10’, for example, to avoid collision with aPLCM used by a prior art mobile terminal. This PLCM is valid in a mobilenetwork where each terminal has a unique PLCM when roaming betweenseparate mobile networks in one country. If a user is roaming in adifferent mobile network instead of his home network or if the user isroaming in another country, a different PLCM generating method can beused.

In this embodiment, a 3^(rd) bit is used as a roaming indicator.Referring to FIG. 10, arbitrary values can be set for 5 bits M38˜M34,respectively. In one embodiment of the present invention, the value forthe 5 bits M34˜M38 are set to ‘11111’, for example. The PLCM_(—)40 ispreferably provided to the physical layer by the signaling layer.

A user may roam from a home network to another mobile network, oranother country. When the user communicates in a home network, theroaming indicator is set, for example, to ‘0’. In such a case, PLCM, asexplained in the foregoing description, is extracted from the IMSI_S.

When the user is roaming in a different mobile network instead of hishome network or when the user is roaming in another country, the roamingindicator is set, for example, to ‘1’. In such a case, the PLCM can begenerated by a method other than the one discussed above, for example.

In one embodiment, an MEID of the mobile terminal is hashed and insertedin a PLCM. For example, a 56-bit MEID is hashed into 39 bits.

A method of hashing a 56-bit MEID into 39 bits of a PLCM is provided inFIG. 11, according to an embodiment of the present invention. 1^(st) and2^(nd) most significant bits are set to ‘10’, for example. A roamingindicator is set to ‘1’, for example, and other 39 bits are set to ahashing value by applying SHA-1 hashing algorithm to a 56-bit MEID, forexample. Then, the PLCM_(—)40 is preferably provided to the physicallayer by the signaling layer.

Referring to FIG. 12, a mobile terminal roaming status can be determinedby comparing MCC and MNC of the terminal to MCC and MNC of the servicingnetwork (S120, S130). If any one of the MCCs and MNCs is different, thenthe user is roaming and a roaming indicator (e.g., 3^(rd) bit of thePLCM) is set to ‘1’, for example (S150), and the PLCM is determinedusing the MEID. Otherwise, if the mobile terminal is in communicationwith a mobile network to which it belongs, the roaming indicator is setto ‘0’, for example (S140), and the PLCM is determined using the IMSI_S.

In one embodiment, 1^(st) to 3^(rd) significant digits of IMSI in FIG. 6are used as MCC and the other 12 digits are used as NMSI that comprisesthe MNC and the MSIN, as shown. In another embodiment, MSIN isconstructed with a 12-digit decimal number from, for example; the leastsignificant 40 bits of PLCM. Referring to FIG. 13, 1^(st) and 2^(nd)bits of the PLCM can be set to ‘00’, for example. Referring to FIG. 14,a 12-digit decimal number can be mapped to a 40-bit binary value.

It will be apparent to one skilled in the art that the preferredembodiments of the present invention can be readily implemented using,for example, the processor 710 or other data or digital processingdevice, either alone or in combination with external support logic.

Although the present invention is described in the context of mobilecommunication, the present invention may also be used in any wirelesscommunication systems using mobile devices, such as PDAs and laptopcomputers equipped with wireless communication capabilities. Moreover,the use of certain terms to describe the present invention should notlimit the scope of the present invention to certain type of mobilecommunication system, such as cdma2000. The present invention may bealso applicable to other wireless communication systems using differentair interfaces and/or physical layers, for example, TDMA, CDMA, FDMA,WCDMA, etc.

The preferred embodiments may be implemented as a method, apparatus orarticle of manufacture using standard programming and/or engineeringtechniques to produce software, firmware, hardware, or any combinationthereof. The term “article of manufacture” as used herein refers to codeor logic implemented in hardware logic (e.g., an integrated circuitchip, Field Programmable Gate Array (FPGA), Application SpecificIntegrated Circuit (ASIC), etc.) or a computer readable medium (e.g.,magnetic storage medium (e.g., hard disk drives, floppy disks, tape,etc.), optical storage (CD-ROMs, optical disks, etc.), volatile andnon-volatile memory devices (e.g., EEPROMs, ROMs, PROMs, RAMs, DRAMs,SRAMs, firmware, programmable logic, etc.). Code in the computerreadable medium is accessed and executed by a processor. The code inwhich preferred embodiments are implemented may further be accessiblethrough a transmission media or from a file server over a network. Insuch cases, the article of manufacture in which the code is implementedmay comprise a transmission media, such as a network transmission line,wireless transmission media, signals propagating through space, radiowaves, infrared signals, etc. Of course, those skilled in the art willrecognize that many modifications may be made to this configurationwithout departing from the scope of the present invention, and that thearticle of manufacture may comprise any information bearing medium knownin the art.

The logic implementation shown in the figures described specificoperations as occurring in a particular order. In alternativeimplementations, certain of the logic operations may be performed in adifferent order, modified or removed and still implement preferredembodiments of the present invention. Moreover, steps may be added tothe above described logic and still conform to implementations of theinvention.

The embodiments described above are to be considered in all aspects asillustrative only and not restrictive in any manner. Thus, otherexemplary embodiments, system architectures, platforms, andimplementations that can support various aspects of the invention may beutilized without departing from the essential characteristics describedherein. These and various other adaptations and combinations of featuresof the embodiments disclosed are within the scope of the invention. Theinvention is defined by the claims and their full scope of equivalents.

1. A method of determining a public long code mask (PLCM) in a mobileterminal used in a mobile communications network, the method comprising:assigning a first PLCM type, when the PLCM for the mobile terminal isbased on an international mobile station identification (IMSI) that isbased on a mobile identification number (MIN) associated with the mobileterminal; and assigning a second PLCM type, when the PLCM for the mobileterminal is based on the IMSI that is based on a value provided by aservice provider. 2-47. (canceled)